1LoadPackage( "RingsForHomalg" ); 2 3LoadPackage( "Modules" ); 4 5Zx := HomalgRingOfIntegersInDefaultCAS( ) * "x"; 6 7R := Zx / "x^2 + 5"; 8 9I := HomalgMatrix( "[ 2, 1+x ]", 2, 1, R ); 10 11I := LeftSubmodule( I ); 12 13M := UnderlyingObject( I ); 14 15e := CoveringEpi( M ); 16 17s := PreInverse( e ); 18 19a := PreCompose( s, e ); 20 21IsIsomorphism( a ); 22 23DecideZero( a ); 24 25N := Hom( R, M ); 26 27f := CoveringEpi( N ); 28 29t := PreInverse( f ); 30 31b := PreCompose( t, f ); 32 33IsIsomorphism( b ); 34 35DecideZero( b ); 36 37